Wadleigh and Richards 425 



magnesium, 10.3; potassium, 13.4; manganese, 0.3; nitrogen, 2.6; and 

 sulfur, 17.8. Losses from a Muskinghum silt loam averaged lower for 

 calcium, potassium, and sulfur but higher for nitrogen. Even though 

 some data indicate that nutrient loss by leaching may be large, these 

 observations do not warrant such a conclusion. Kohnke (70) has em- 

 phasized that losses of plant nutrients in drainage are appreciably less 

 than those possible from surface runoff. 



When fertilizer is applied to a soil and conditions conducive to leach- 

 ing prevail, there is usually an increase in solute in the leachate, but 

 the proportions of the component ions of the solute usually deviate 

 from those in the added fertilizer due to base-exchange reactions. This 

 is well illustrated by the observations of Volk and Bell (126) on lysime- 

 ters filled with Lakeland loamy fine sand having a base-exchange ca- 

 pacity of 3.0 m.e. per 100 g. Various sodium, magnesium, and potassium 

 salts were applied to different lysimeters. Though no calcium was ap- 

 plied, it was invariably the predominant cation in the leachate. Even 

 when 16.39 inches of leachate had been collected from the 4-foot col- 

 umns of soil, only about 1 per cent of the potassium applied was found 

 in the leachate, whereas about 65 per cent of applied sodium and about 

 30 per cent of applied magnesium appeared in the leachate. Chlorides 

 were recovered almost quantitatively; about 50 per cent applied sulfate 

 appeared in the leachate and, in most instances, more than twice as 

 much nitrate was recovered as was applied. There was practically no 

 difference in the proportions or amounts of cations in the leachate 

 whether the salts added to the soil were chlorides or nitrates, but when 

 sulfate salts were applied, there was a marked decrease in the loss of 

 calcium. 



The foregoing data emphasize that leaching losses of nutrients may 

 be high on a light soil under heavy rainfall. Thus, the standard treat- 

 ment of Volk and Bell (126) corresponded to an application of 31 

 pounds of nitrogen per acre, and the leachate from this treatment cor- 

 responded to a loss of 74 pounds of nitrogen per acre from fallow soil 

 over a five-month period. It is commonly observed that nitrogen defi- 

 ciency may readily develop on light soils during wet seasons. There is 

 increasing evidence that these same conditions are conducive to the 

 development of magnesium deficiency. Hester et al. {59) noted that 



